The invention is directed to a magnet core for current sensors composed of a soft-magnetic alloy, and is also directed to a current sensor containing this magnet core.
Magnet cores for compensation current sensors composed of soft-magnetic alloys have been known for a longer time. What is characteristic of these cores is that a magnetic field sensor, for example, a Hall element, is arranged in the interior of the secondary leg of the core or in an air gap. In general, the secondary leg encompassing the sensor is inserted into a compensation coil. In known embodiments of compensation current sensors, the magnet cores are executed either as slotted toroidal cores or as sheets stacked in alternation.
The application of a winding for the compensation coil onto the secondary leg is very involved in the case of toroidal cores composed of slotted sheets.
The magnet cores of the second type are of sheets stacked in alternation and can, in fact, be produced without involved winding by plugging the core into a prefabricated coil; however, this procedure requires the punching of the core plates from a band or from sheet metal. During the punching, a high percentage of the core material usually remains as waste. This lost must be either compensated by a higher outlay for material or it is necessary to return the lost material to the initial material on the basis of a recycling step. Corresponding measures, however, are meaningful only to a limited extent due to economic considerations.
The ultimately stacked core sheets of the second type are, as known, produced from rectangularly shaped sheets that comprise a slot in the region of the secondary leg for the acceptance of the magnetic field sensor. The disadvantages recited in the preceding paragraph arising from manufactured due to punching likewise apply to the core plates cited here.
An object of the present invention is to create a magnet core of the latter type that can be economically manufactured and that does not exhibit the disadvantages of the known magnet cores for current sensors.
This object is inventively achieved by a magnet core for current sensors composed of a soft-magnetic alloy composed of at least two bent or buckled alloy tape sections.
The inventive magnet core is preferably composed of two bent alloy band sections.
The invention is also directed to a current sensor that is characterized in that it contains a magnet core according to the invention.
The invention is also directed to a method for manufacturing the composite magnet core of the invention, comprising the steps:
a) manufacturing an alloy band of a soft-magnetic material, bending or buckling the alloy band in such a way that at least two alloy band sections arise that comprise an angle of 90xc2x0 or 180xc2x0 relative to one another, separating or cutting the band to the desired length, whereby the separation or cutting can ensue before or after the bending or buckling, and preferably
b) joining of at least two bands produced according to Step a) to form a magnet core.
It is a particular advantage of the present invention that, by replacing the traditional core plates with the inventively shaped band sections, the punching can be eliminated. As a result thereof, the waste arising of necessity during punching is avoided in a simple way. Advantageously, the soft-magnetic material that is utilized can be fully exploited without loss of material.
Dependent on the application for which the inventive core is to be utilized, a person skilled in the artxe2x80x94in conformity with the method of the inventionxe2x80x94can set the cross-section of the core to the demands prescribed by the application in an especially simple way. The desired cross-section can be achieved by suitable, multiple buckling or bending of the band.
The invention is explained in greater detail below with reference to the drawings.